1. Field of the Invention
The present invention relates to a hybridly integrated component that includes at least one ASIC (application-specific integrated circuit) element having a processed front side, a first MEMS (micro-electromechanical systems) element having a micromechanical structure, and a first cap wafer. The micromechanical structure of the first MEMS element extends over the entire thickness of the MEMS substrate and includes at least one deflectable structural element. The first MEMS element is mounted on the processed front side of the ASIC element in such a way that a gap exists between the micromechanical structure and the ASIC element. The first cap wafer is mounted over the micromechanical structure of the first MEMS element. In addition, the present invention relates to a method for producing such a hybridly integrated component.
2. Description of the Related Art
Components having MEMS components have been mass-produced for many years for a wide variety of applications, for example in the area of automotive technology and consumer electronics. The miniaturization of the components has become increasingly important. The miniaturization contributes substantially to reducing the production costs of the components and thus also of the end devices. In addition, in particular in the area of consumer electronics more and more functions—and therefore components—are to be incorporated into an end device, while the end devices themselves become ever smaller. Consequently, less and less space is available on the application circuit boards for the individual components.
In practical use, various miniaturization designs for sensor components are known that provide an integration of the micromechanically realized sensor function and the circuit-based processing and evaluation of the sensor signals in a component. Besides the lateral integration of the MEMS function and the ASIC function on a common chip, there are also designs for so-called vertical hybrid integration, according to which a chip stack is formed of an ASIC, a MEMS, and a cap wafer.
Such a vertically integrated component and a method for its production are described in US Patent Application Publication No. 2011/0049652 A1. The known method provides the bonding of the initial substrate for the MEMS element on an already-processed ASIC substrate. Only after this is a micromechanical structure produced in the MEMS substrate, including at least one deflectable structural element. Independently of this, a cap wafer is structured and is prepared for mounting over the micromechanical structure of the MEMS substrate and on the ASIC substrate. The cap wafer processed in this way is bonded onto the ASIC substrate after the structuring of the MEMS substrate, so that the micromechanical structure between the ASIC substrate and the cap wafer is enclosed so as to be hermetically sealed.
The known component design enables an economical mass production of robust components having a micromechanical function and a signal processing circuit, because here not only are the individual components—MEMS element, cap, and ASIC—produced in the wafer composite, but their assembly to form a component on the wafer level is also realized. The MEMS functions and the ASIC functions can be tested on the wafer level, and even the calibration of the individual components can be carried out before their separation on the wafer level. Moreover, due to the stacked construction the known components require a comparatively small mounting surface, which has an advantageous effect on the production costs of the end devices.
The known component design presupposes a good surface matching between the MEMS element and the ASIC element. Accordingly, the miniaturization effect and the cost advantage connected therewith is particularly large if the micromechanical MEMS function and the circuit-based ASIC function have a comparable surface requirement. Only in this case can both elements be realized without wasting chip surface.
However, in a series of applications known from practical use, the micromechanical structure of the MEMS element takes up significantly larger chip surface than is required for the realization of the associated ASIC function. Examples of this include rotational rate sensors and so-called IMUs (Inertial Measurement Units), where rotational rate sensor elements and acceleration sensor elements are integrated with relatively large micromechanical structures in one component.